Small-sized mobile devices have spread on the worldwide basis and at the same time, with a drastic progress of high-speed information transmission networks, demand for small-sized large-capacity nonvolatile memory has been rapidly expanding. Among others, particularly NAND type flash memory and small-sized HDD (hard disk drive) have achieved rapid progress in recording density and have formed a large market.
Under these circumstances, some ideas on new memory with a purpose of drastically exceeding the limit of recording density are proposed.
Among them, memory using a resistance change material having a low resistance state and a high resistance state is proposed. And a technology in which a recording layer is formed of a composite compound having at least two types of positive ion elements and at least one type of the positive ion element is a transition element having a d orbital incompletely filled with electrons is disclosed (e.g., JP-A 2008-84512(Kokai)).
In this technology, a state of vacancy of a metal element contained in the recording layer is not considered, and there is a room for improvement in terms of stability of an operation.